MOD = 998244353

N = int(input())
S = input()

def func(n):
    dp = [[0]*2 for _ in range(N+2)]
    dp[0][0] = 1
    for i in range(N):
        dp[i+1][0] += dp[i][0]
        dp[i+1][0] %= MOD
        dp[i+1][1] += dp[i][1]
        dp[i+1][1] %= MOD
        if S[i] == "0":
            dp[min(i+1+n, N+1)][0] += dp[i][0]
            dp[min(i+1+n, N+1)][0] %= MOD
        if S[i] == "1":
            dp[min(i+1+n, N+1)][1] += dp[i][0]
            dp[min(i+1+n, N+1)][1] %= MOD
        add = dp[i][0]
        if 0 <= i-n:
            add -= dp[i-n][0]
            add %= MOD
        dp[i+1][0] += add
        dp[i+1][0] %= MOD
    ans = 0
    for i in range(1, N+1):
        if 2 <= N-i:
            ans += (dp[i][1]-dp[i-1][1])*POW[N-i-1]%MOD
            ans %= MOD
        else:
            ans += dp[i][1]-dp[i-1][1]
            ans %= MOD
    return ans

POW = [1]
for _ in range(N):
    POW.append(POW[-1]*2%MOD)

ans = 0
for i in range(N):
    ans += func(i)*POW[i]%MOD
    ans %= MOD

print(ans)